just: use released artifacts for demodir

When demoing Contrast, we usually want a stable software version with a
minimum amount of surprises, so we would like to use the released binary
and coordinator YAML for that. This commit adds a script that downloads
the artifacts, which is a bit complicated because of visibility
restrictions, and modifies the just target to use this script.

We're deliberately hardcoding the namespace into the demodir recipe,
instead of reading it from the copied YAML, because we're going to
switch to resourcegen eventually, which will make the demodir recipe
decide the namespace. At that point, we can just pass the namespace to
the new script and resourcegen.

justfile

@@ -187,16 +187,18 @@ fmt:
 lint:
     nix run .#scripts.golangci-lint -- run
 
-demodir cli=default_cli: undeploy coordinator initializer
+demodir: coordinator initializer
     #!/usr/bin/env bash
     d=$(mktemp -d)
+    namespace=edg-default
     echo "Creating demo directory at ${d}"
-    nix build .#{{ cli }}
-    cp ./result-cli/bin/contrast "${d}/contrast"
     cp -R ./deployments/emojivoto "${d}/deployment"
+    rm -f "${d}/deployment/coordinator.yml"
     nix run .#scripts.patch-contrast-image-hashes -- "${d}/deployment"
     nix run .#kypatch images -- "${d}/deployment" \
         --replace ghcr.io/edgelesssys ${container_registry}
+    # TODO(burgerdev): set namespace on generated resources, too.
+    nix run .#scripts.fetch-latest-contrast -- "${namespace}" "${d}"
     echo "Demo directory ready at ${d}"
 
 # Cleanup auxiliary files, caches etc.

packages/scripts.nix

@@ -168,4 +168,24 @@ with pkgs;
       popd >/dev/null
     '';
   };
+
+  fetch-latest-contrast = writeShellApplication {
+    name = "fetch-latest-contrast";
+    runtimeInputs = [
+      jq
+      github-cli
+    ];
+    text = ''
+      namespace=$1
+      targetDir=$2
+      release=$(gh release list --json name,isLatest | jq -r '.[] | select(.isLatest) | .name')
+      gh release download "$release" \
+        --repo edgelesssys/contrast \
+        -D "$targetDir" \
+        --skip-existing
+      chmod a+x "$targetDir/contrast"
+
+      yq -i ".metadata.namespace = \"$namespace\"" "$targetDir/coordinator.yaml"
+    '';
+  };
 }